Resumen de The inventions of José Ruiz Castizo: the planimeter

Claudia Teresa Vela Urrego, María Ángeles Martínez García

• The aim of this work is to describe the invention of a planimeter by the Spanish physicist-mathematician José Ruiz-Castizo Ariza (1857-1929). He was a professor of Mecánica Racional in the Universities of Zaragoza (1896- 1905) and Madrid (1905-1929). Before getting his chair, being assistant professor of Física Superior in the Faculty of Sciences in Madrid (1892-1896), he invented a planimeter the analytical basis of which was different from others known then. During his first years in Zaragoza, he published an extensive article explaining the theoretical foundations and the phases followed in its design, from the first prototype to the final result. RuizCastizo’s planimeter, which ameliorated the performance qualities of the ones by foreign authors that were being used in Spain, was built in Switzerland in 1897, tested in the Public Works Office (Oficina de Obras Públicas) in Zaragoza and used in other technical Offices, including the local delegations of the National Geographic Institute (Instituto Geográfico Nacional).